Microplastics on the beach. The U.S. National Oceanic & Atmospheric Administration classifies microplastics as being smaller than 5 millimeters. / Maia McGuire

Walking along the beach, you’ll likely see a variety of trash. Some is, of course, obvious: bottles, bags, six-pack rings and the like. Much of that detritus is made of plastic, and it creates some big problems: Even if you can’t see the small pieces of plastic, they don’t degrade. Worse: They’re found in a lot of places in addition to the oceans.

“The term ‘microplastic’ refers to pieces of plastic that are smaller than 5 millimeters, but many microplastics start off as larger plastic objects,” says Maia McGuire, Ph.D. “Petroleum-based plastic never actually biodegrades. With time, it will degrade into smaller and smaller pieces, eventually seeming to disappear — because they get too small to see with the naked eye — but those tiny pieces are still plastic.”

Maia McGuire in a classroom. / Courtesy UF/IFAS

McGuire serves as the multi-county Sea Grant agent for the University of Florida’s Institute of Food and Agricultural Sciences Extension office in Bunnell, about 70 miles south of Jacksonville.

She holds a doctoral degree in marine biology and fisheries from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science. Her bachelor-of-science degree, in marine biology, is from the Florida Institute of Technology.

In 2015, she wrote a grant proposal to the U.S. National Oceanic & Atmospheric Administration to fund the Florida Microplastic Awareness Project (sfyl.ifas.ufl.edu/flagler/marine-and-coastal/microplastics). That grant was funded and, although it ended in 2016, the education/outreach project continues.

Danger comes in small pieces

A tiny piece of clear plastic as seen under a microscope. / Maia McGuire

Microplastics could be harming marine life — all the way up and down the food chain — McGuire explains: “Depending on the type of marine life, there are concerns that microplastics could impact the ability of organisms to feed properly — for example, by clogging their digestive systems — and/or that plastics could introduce chemical pollutants into organisms.

“Some of these pollutants are suspected endocrine disruptors; or are known to be toxic, such as PCBs and DDTs. Microplastics are a particular concern because very small animals, at the base of the food chain, can and do eat them. So there is the potential for effects to be magnified up the food chain.”

Another concern is the widespread distribution of microplastics, according to McGuire. This topic arose at the annual International Marine Debris Conference, held in March in San Diego, she says.

“Microplastics do not seem to be concentrated in particular areas — rather, they seem to be quite broadly distributed. This is not just the case in Florida, but globally. There was some discussion at the International Marine Debris Conference that the contribution of aerial transport of microplastics may be underestimated, and that this could be resulting in the relatively even distribution of microplastics — even in remote areas where microplastics would be expected to be rare.”

Their presence is not limited to the oceans. “We have found microplastics in coastal waters all around Florida, and in springs and in lakes in the middle of the state,” McGuire says.

Other problems with microplastics

The main use for smaller pieces of plastic is as materials for artistic creations. This was on display at the March 2018 International Marine Debris Conference. / Maia McGuire

Even if microplastics could be collected easily — they can’t — what can they be used for? “Not much,” McGuire says. “Some ocean- or beach-collected plastics can be sorted and used to make into other plastic products. But microplastics are so small, and difficult to identify as to the type of plastic resin that they contain, that the main use I have seen for them is in artistic endeavors.”

Yet another issue is the sheer amount of plastics produced. According to the UF/IFAS report “Contaminants in the Urban Environment: Microplastics,” which McGuire co-authored, “Since the mid-twentieth century, plastic has been a boon to humanity and an integral part of our modern lives. However, plastic debris is a major concern due to its abundance and persistence in the environment. For example, 32 million tons of plastic waste was generated in the United States alone in 2012.”

Another challenge, according to the report: “microplastics additives in some personal-care products (such as toothpaste) and microplastics fibers from synthetic fabrics such as polyester and polyamide are discarded during clothes washing and end up in wastewater.” Because wastewater-treatment plants cannot remove such tiny particles, they remain in suspension in the liquid and eventually are discharged into whatever body of water gets the effluent.

The four-page report ends with this thought-provoking passage: “Our understanding of potential future trends in the abundance of microplastics is limited, while contamination by microplastics is likely to continue to grow. Work is needed to reduce and eliminate sources and pathways of microplastics exposure.”

To download and read the report “Contaminants in the Urban Environment: Microplastics,” visit edis.ifas.ufl.edu/pdffiles/SS/SS64900.pdf.